Study On Ecohydrological Moedl And Evolution Law In Hungriness Area Of Northern Shaanxi

The hungriness area of Northern Shaanxi is located at the southern adge of Mu Us Desert,belonging to the arid and semi-arid region.There is a serious lack of ground vegetation,severe climatic conditions,and a fragile ecological environment.Therefore,studying the evolution process of its eco-hydrological system can provide scientific basis for the economic and social development of the important energy and chemical bases in Northern Shaanxi.It has important theoretical significance and application values.This paper takes the hungriness area of Northern Shaanxi as the research object,analyzes the evolution law of meteorology,ecology and hydrology,constructs the eco-hydrological evolution model of the hungriness area of northern Shaanxi,and simulates a variety of future scenarios to study the response to the changing environment in the hungriness area of northern Shaanxi.The main results obtained in this paper are as follows:(1)Revealing the evolution of precipitation and evaporation in the study area by statistics and nonlinear methods,the results show that:the increasing trend of precipitation is fluctuating year by year and the future precipitation will continue to increase at the current stage;the precipitation has a cycle of 3-year,9-year and 15-year,which has change-point in 2013 and 2015.The declining trend of evaporation is fluctuating year by year and the future evaporation will continue to decline at the current stage;the evaporation has a cycle of 9-year;and it mutated in 2011.(2)Revealing the law of soil water content and vegetation index NDVI by statistical method,the results show that:the multi-year average soil volume water content with the distance of 5cm under the earth in the hungriness area of Northern Shaanxi is 14.53%,which has an increasing trend year by year.The interannual variation of vegetation coverage index NDVI shows an overall upward trend,indicating that the vegetation coverage is increasing year by year;the seasonal changes of NDVI are distinct,and the overall performance is summer>autumn>spring>winter.(3)Improving the Ecohydrological Evolution Model on Riparian Vegetation in lower Tarim River(REV Model).In view of the characteristics of the hungriness area in Northern Shaanxi,the process of soil water movement and replenishment of soil water by precipitation are considered.The eco-hydrological evolution model in the hungriness area in Northern Shaanxi is constructed by considering the process of soil water movement and the recharge of soil water by precipitation.(4)Simulating the process of eco-hydrological evolution in study area in the past.Using eco-hydrological evolution model in hungriness area of Northern Shaanxi,the eco-hydrological process in the study area is simulated from 2001 to 2016.The vegetation coverage and soli water observation data are used to verify the simulation results.The verification results show that the simulation accuracy of the model basically meets the requirement and can reflect the evolution process of soil water and vegetation coverage in recent decades.(5)Simulating the process of eco-hydrological evolution in study area in the future.A set of future environmental change scenarios is set up.Using the model established in this paper,the vegetation coverage and soil water changes under the two scenarios of natural environment change and human intervention in environmental changes are simulated.Suggestions for ecological protection of desert areas are proposed.